In conventional paint production, for producing water paints or paints that contain poorly compatible additives, paddle-blade agitators and high-speed dissolvers (also called dispersers) are often used because of their high shear force. However, paddle-blade agitators and high-speed dissolvers are problematic in that when the number of rotations of the paddle blades or dissolver vanes is increased, entrainment of air bubbles is caused due to a vortex, and, on the other hand, when processing at a reduced number of rotations, it is difficult to obtain the shear force necessary to disperse pigments for water paint or poorly compatible additives in a paint medium. For this reason, in such paint-producing processes where dispersion is difficult, homomixers, i.e., rotor/stator-type homogenizers, which cause less air bubble entrainment are used in place of high-speed dissolvers, etc. (see, e.g., patent document 1).    Patent document 1: Japanese Unexamined Patent Publication No. 1982-42324